Change in coreboot[master]: arch/x86: Add ebda read/write functions into EBDA library

[Subrata Banik (Code Review)]

Subrata Banik has uploaded this change for review. ( https://review.coreboot.org/21536

Change subject: arch/x86: Add ebda read/write functions into EBDA library
......................................................................

arch/x86: Add ebda read/write functions into EBDA library

This patch provides new APIs to write into EBDA area
and read from EBDA area based on user input structure.

Change-Id: I26d5c0ba82c842f0b734a8e0f03abf148737c5c4
Signed-off-by: Subrata Banik 
---
M src/arch/x86/ebda.c
M src/arch/x86/include/arch/ebda.h
2 files changed, 67 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/36/21536/1

diff --git a/src/arch/x86/ebda.c b/src/arch/x86/ebda.c
index c828aa4..61db30e 100644
--- a/src/arch/x86/ebda.c
+++ b/src/arch/x86/ebda.c
@@ -20,6 +20,58 @@
 #include <arch/ebda.h>
 #include <arch/acpi.h>
 #include <commonlib/endian.h>
+#include <console/console.h>
+
+static void *get_ebda_start(void)
+{
+	return (void *)((uintptr_t)DEFAULT_EBDA_SEGMENT << 4);
+}
+
+/*
+ * EBDA area is representing a 1KB memory area just below
+ * the top of conventional memory (below 1MB)
+ */
+
+/*
+ * write_ebda_data is a wrapper function to write into EBDA area
+ * in DWORD mode.
+ *
+ * data = data to be written into EBDA area
+ * length = input data size in bytes
+ */
+void write_ebda_data(void *data, size_t length)
+{
+	void *ebda;
+	int count = 0;
+
+	if (length > DEFAULT_EBDA_SIZE)
+		die("Input data width is more than EBDA size!");
+
+	ebda = get_ebda_start();
+
+	while (count < length) {
+		write_le32(ebda, *((uint32_t *)(data + count)));
+		count += sizeof(uint32_t);
+		ebda += sizeof(uint32_t);
+	}
+}
+
+/*
+ * read_ebda_data is a wrapper function to read from EBDA area
+ *
+ * return data read from EBDA area
+ */
+void *read_ebda_data(size_t length)
+{
+	void *ebda;
+	static void *data;
+
+	ebda = get_ebda_start();
+
+	memcpy(data, ebda, length);
+
+	return data;
+}

void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size)
 {
@@ -36,7 +88,7 @@

low_memory_kb = low_memory_size >> 10;
    ebda_kb = ebda_size >> 10;
-	ebda = (void *)((uintptr_t)ebda_segment << 4);
+	ebda = get_ebda_start();

/* clear BIOS DATA AREA */
    zero_n(X86_BDA_BASE, X86_BDA_SIZE);
diff --git a/src/arch/x86/include/arch/ebda.h b/src/arch/x86/include/arch/ebda.h
index 428bc92..7e2e4fa 100644
--- a/src/arch/x86/include/arch/ebda.h
+++ b/src/arch/x86/include/arch/ebda.h
@@ -31,5 +31,19 @@

void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size);
 void setup_default_ebda(void);
+/*
+ * write_ebda_data is a wrapper function to write into EBDA area
+ * in DWORD mode.
+ *
+ * data = data to be written into EBDA area
+ * length = input data size in bytes
+ */
+void write_ebda_data(void *data, size_t length);
+/*
+ * read_ebda_data is a wrapper function to read from EBDA area
+ *
+ * return data read from EBDA area
+ */
+void *read_ebda_data(size_t length);

#endif